Driver unit for loud-speakers



ch 27 1951 s, LEVY 2,546,343

DRIVER UNIT FOR LOUD-SPEAKERS Filed Dec. 51, 1946 5 Sheets-Sheet 1 INVENTOR ATTORNEYS March 2?, 31951 s. E. LEVY 9 9 DRIVER UNIT FOR LOUD-SPEAKERS Filed Dec. 31, 1946 3 Sheets-Sheet 2 Tic. 2.

INVENTOR SIDNEY E. LEVY BY f' a jy ATTORNEYS March 27, 1951 s. E. LEVY 2,545,343

DRIVER UNIT FOR LOUD-SPEAKERS Filed Dec. 31, 1946 3 Sheets-Sheet 3 4 h J J I: 4/

' T LETE.

INVENTOR SIDNEY ELEVY BY ATTORNEYS Patented Mar. 27, 195i U NITED S TATES PATENT OFFICE 2,546,343 DRIVER Uhi'r roe LO D-SPEA ERS Sidney E. Levy, Brooklyn, ,N. Y, as signo r to University Loudspeakerd'ine, New York, N. Y., a corporation of New York 7 Apn'i'camneemter 31, 1946, Serial N6. 719,431

13 Claims. (o1. 179- 1155) ing application discloses an extremely effective 7 type of magnet comprising inner and outer poles having an annular groove separating them, the structure being so designed that cross section it resembles an E. Slots areprovided in the outer surface of the magnet at the end of a pair of intersecting diameters to prevent the setting up of stresses during the casting of the metal 'and to form means for readily mounting themagnet in a speaker.

My present invention is directed to a housing and other parts cooperating with a magnet of the type above mentioned to form a complete loudspeaker driver uni't. This unit is so designed as to enclose the rear of the speaker diaphragm completely, to assure that the volume of airto the rear side of the speaker diaphragm wil ,prb ducethe proper response of the d'iaphra gm under the energiz'ation of the voice-coil. Further, the construction is such as to make the entire driver unit very readily assembled and completely weatherproof when so assembled.

7 It is an object of the invention to provide a loudspeaker driver unit utilizing a magnet having an E-shaped cross section and soarran'ged to give a definite air volume to the rear'of the speaker diaphragm by virtue of an enclosing housing.

It is another object of a the invention to produce a loudspeaker driver-unit which --may be readily assembled, especially with respect to the location of the voice coil in the usual magnetic gap.

It is another object of the invention to pro vide a magnet structure and cooperating pole pieces having passages therein to permit a corn trolled movement of air through the magnet structure and into a confinedspace of predetermined volume in the housing.

Other objects and features of the invention -will appear when the following description is considered. in connection with the annexed-drawings,--in which:

Figure'l is a top plan view of the loudspeaker of the instant invention; I

Figure 2;is a-verticalcros's sectional view of the loudspeaker of Figure l, the section being 2 taken on the plane of the lines 2- -2 of Figrs 4 t Figure 3 is a fragmentary cross sectional view on the plane .of the lines 3 3 of Figure 2 showing particularly agroove in the outer pole piece which jaeilitates the locating of the rea'ssembled sound headso that the diaphragm and voice coilthereon are accurately centered with respect totheiout'er pole piece. V

Figure Fl. is a horizontal cross sectional view ot the speaker, of Figures 1 and 2 taken on the plane of the lines 4 4 of Figure 2 and showin'g particularlya channel in the inner pole piece to permitair :to mov'e from the space immediately behind the diaphragm to the slots in the magnet and thence to the casing, as-well as the mode or" mounting the magnet to the cover of the structure fand axin the base'a'nd cover of the ho'using striictu're together; and I I H Figur 5 i sa botto mplan viewof the magnet pole jp" es within which the air gap is formed. "Refer r g now to the drawings the speaker driver unijt comprises the magnet it which as clearly shown is generally E shaped in :cross section and is provided with the slots i'i through which the bolts [2 extend. Bolts I2 thread into tapped holes 13 iii the upper member M of the housing and hold the magnet Iii together with cooperating parts about to be described in position with respect to the housing.

The inner circular pole piece 15 and outer annular p'ole piece it are fastenedtogether by means of the arc-shaped, non-magnetic member i1 which as clearly shown in Figure 2 extends across th'e 'a'n'lniilar gap 18. The pole pieces are positionedjipfoh the magnet iii prior to the magnetization thereef which magnetization may be accbmplish'ed by any-of the modes indicated in my copending application abovementione'd. The magnetizing winding ig removed subsequent to the magnetizingoperation and consequently is not shown in the instant drawings. After this magnetizing operation has been completed the 'magnet l0 and th'epole pieces 15 and [B are so firmly held together that they comprise a single unit.

1 01s piece is is provided with g oo e in in its upper surface in which groove there is seated a downwardly depending fiangeil of the sound head subass'enibly 22, Theouter surface of the head assemblyis provided with projections which meet with corresponding depressions-in the inner surface of housing It as-iiidic'ated "by the dotted lines at' lg whereby the location of the headis made definite, and the assembly of the he ad-afid cooperating parts into the housing H! are facilitated.

The alignment of the sound head into the cover l4 may be achieved by a number of obvious means. The above is merely one of a number of suitable means.

Cemented to an annular rim 23 of sound head 22 is a diaphragm 24 having a depending portion 25 which supports the voice coil within the magnetic gap l8.

Between the portion of the diaphragm cemented to the rim 23 and the outer pole piece i6 is a gasket 26 which prevents the leakage of any air from the space behind the diaphragm (i. e. beneath the diaphragm as seen in Figure 2), and serves to space the diaphragm a discrete distance above the keeper Hi, to prevent striking during extreme movements of the diaphragm. The upper housing member 14 is provided with a groove 2i in which an annular compressible gasket 28 is positioned and against which rim 30 on the sound head 22 seats, thus preventing water or moisture which might enter the throat, from entering into the vital interior of the driver unit.

By virtue of the utilization of the annular groove 2c in the annular pole piece It the facility with which the voice coil may be inserted in the magnetic gap is greatly increased since it is only necessary to locate the flange 2| in the groove 28 and this automatically positions the head and diaphragm thereon so that the voice coil is uniformly centered in the magnetic gap. This is assured since the diaphragm i pre-assembled into the head by means of suitable fixtures so the voice coil is concentric with respect to the overhanging flange 2 I.

It should perhaps be mentioned at this point that the inner circular portion of the E-shaped magnet I is beveled on its outer edges as is shown clearly at 3| in order to provide space for the member ll. This beveling is at such angle, however, that there is no appreciable diminution of flux across the gap. It has been found by tests that the bevel should not be at an angle greater than forty-five degrees from the horizontal.

When the magnet l0, pole pieces l and I6, head 22 and diaphragm 24 have been assembled as indicated above, they are inserted into the upper housing 14 and bolted into place by means of the bolts l2 which bolts have washers 32 beneath their heads, these washers extending across slots II as may be most clearly seen in Figure 4.

In order to provide for the escape of the rear wave pressure exerted by the diaphragm, the central pole piece i5 is provided with a hole 33 in the center thereof, this hole communicating with a slot 34 extending across the inner circular portion of the magnet is and communicating with the annular groove in that magnet and,

in turn, with the slots H in the magnet.

This rear air escapement may also be achieved by providing a groove 39 in the pole piece l5 instead of or in addition to the groove 34 across the center pole face.

By this means as well as by means of the openings 35 in the member I! free movement of air between the space immediately behind the diaphragm and the outer enclosing housing is accomplished. Further, the cross sectional area of the slots 34 and 39 and the openings 35 may be dimensioned to serve as an acoustic resistance and thereby adjust the speaker frequency response.

The lower housing member 36 is provided at its upper edge with a rubber gasket 31, see Figures 2 and 4, the rubber gasket being located within a rim 33 on the housing 36 and being held in position by being also placed in grooves 40 in the mounting bosses 4|. By means of this arrangement there is a metal to metal seal between the outwardly extending rim 42 of the upper housing member l4 and the rim 38 of lower housing member 36. At the same time there is a metal to rubber seal between the rim 42 and the gasket 3'3. The mounting bosses 4| are formed integrally with the housing member 3'5 and have the form particularly shown in Figures 2 and 4. These bosses are provided with holes 43 which mate with similar holes 44 in mounting bosses 45 formed integrally with the housing member l4. Thus, upon assembling the two housing members together in their proper relationship bolts may be placed in the holes 43 and 4 1 and nuts placed on these bolts at their lower ends, thereby firmly clamping the two housing members together in proper relationship. The bosses or ribs 4! may be provided with an ofiset portion 46 as shown in Figure 2 to form an additional support for the magnet.

The leads from the voice coil may be connected in any suitable manner as by means of terminals fixed to but insulated from the rim 23 of sound head 22 and are led thence downwardly through the housing and to the terminals 47, which terminals are suitably fixed to an insulating plate 48 mounted on the reentrant portion 56 of the lower housing-member 3'3. The external leads are connected to the terminals 55 which of course are connected in any suitable manner (not shown) to the inner terminals ill. The external leads are then lead out through holes in the cover plate 52, which cover plate is fas-.ened to the re-entrant portion 53 by means of the screws 53-.

Cooperating with the phasing plug portion of the sound head 22 is an anti-crossfire member 66, which member comprises a pair of fins at right angles to each other located in the speaker throat 62 adjacent the plug 53. Any convenient method of mounting the fins 60 may be utilized. However, they are shown in the present instance in slots 6| in the throat portion 62 of the upper housing l4.

While I have described a preferred embodiment of my invention, it will be obvious to those skilled in the art that other modifications may be used and, therefore, I do not wish to be restricted to the particular device shown and described but only within the scope of the appended claims.

What is claimed is:

1. In a driver unit for an electrical transducer, in combination, a sound head comprising a diaphragm carrying a voice coil, an upper housing member, means for fixing the relative position of said upper housing member and said sound head, a generally cylindrical permanent magnet of an E-shaped cross-section, an inner circular pole piece, a concentric outer annular pole piece, means spacing said pole pieces to form an annular magnetic gap, means mounting said pole pieces across the open face of the E of said magnet, an annular groove in said outer pole piece, an annular flange on said sound head engaging said annular groove and positioning the pole pieces with respect to said sound head, with the voice coil in the amiular magnetic gap, a plurality of slots extending through the rim of said E-shaped magnet, and bolts extending through sai l ts e di g sa dl firsr h usin iehsa dv id gsqf f a t i'i fix q ro i iea a r Ina driver unit, for an, electrical transducer,

in combination, a sound head comprising a diaphragm carrying. avoice coil, an upper housing member, means for fixing the. relative. position of, said upper housing member. and said, sound head, a. generally cylindrical permanent magnet of an E-shaped cross-section, anv inner circular pole piece, a concentric outer annular pole piece, Inearis spacing said pole pieces to. form, an annular magnetic gap, means mounting said pole pieces across theopen face of. theE oflsaid magnet, a central axial-hole in said inner pole-piece, aQg'roove across the inner. circular pole of said magnet communicating with said hole and cornm unic ating also with theannular groov in. said magnet, saidgroove being of a size to form an acoustic resistance, an annular groove in said outer. pole piece, and an annular flange on said soundhead engaging said annular groove and positioning the poll pieces with respect to said sound head, with, the voice coil in the annular magntic gap.

3. Inla, driver unit for-an electrical transducer, in combination, a sound head comprising a diaphragm carrying, a voice coil, an upper housing. member, nians fOr fixing the relative ension of said upperhousing member and said sound head, a generally cylindrical permanent magnet of an E-shaped cross-section, an inner circular pole piece, aconcentric outer annular pole piece, means spacing said pole pieces. to form an annular magnetic gap, means mounting said polepi'ecesacross theopen face of the E of said magnet, a central axial holein said-inner pole p e ,a groove across the,innercircular pole of said. magnet comnrunicating with said hole and communicating also with the annular groove-in said magnet, said groove beingof asize to form an acoustic resistance, an annular groove, in said outer pole piece, an annular flangev on saidsound head engaging saidannular groove and position- 'ing the pole pieces with respectto said sound head with thevoice coil in; the annular magnetic gap,v slots in the rim ofsaid E -shaped magnet, said slots communicating with said groove in said inner pole, meansfixing-said magnet and sound head" in position relative to said upperhousing, and a llower housingof predetermined volume affixed tosaid up pei'housing at the peripheries thereof, said volume of said lower housing serving ito' improve theresponse of the transducer.

4'." Inadriver unit for an electrical transducer,

in combination, a soundheadcomprising a diaphragmfcarrying avoicecoil, aniupper housing mernloer, means for fixing the relative position of saidupper,housingmemher and said sound-head, a generallycylindrical permanent-magnet of-an E.-shaped cross-section, an inner circular pole piece at. concentric outer, annular pole piece, means spacing said pole pieces to form an-annularfmagnetic gap, means mounting said pole pieces across the openface of; th E of said magnet, a central axial holein said inner keeper, a groove across the face of said inner pole piece adjacent the inner circular magnetpole and cornrnunicating with-said hole and communicating aisle wit he annular. groove of said; E shaped magnet, said first groove ,being of a sizeto form an, acoustic resistance; an annular, groove in said outer pole pie e; and'an annular flange on; said m iin ai 'iinu a cerwr and positioning the'pole p'i'eces with respect to said soun head, with the voi e. c ii in the, an uiar ma net c. ap.-

5 In adriycr unit for an, electrical transducer, in. combination, a soundhfiad comprising a dianhmgm carry a voic co a up r usin member means for fixing the relative position of said upper housing member and said sound head, a generally, cylindrical, permanent magnet o f, an E-shapcd cross section, an inner, circular pole piece, a, concentric outer annular pole piece, means spacing said pole pieces to form an annular magnetic gap, means mounting said pole pieces across theopen face of the E of, said magnet, a central axial hole in said inner pole piece, a groove across the face of said inner pole piece adjacent the inner circular magnet pole andcommunicating with, said hole, and communicating also with the annular, groove of, said' E-shaped magnet, saidfirstgroove being of a size to form an acoustic resistance, anannular groove in said outer keeper, an annular flange on said sound head engaging said annular groove and positioning the pole pieces with respect to said sound head, with the voice coil in the annular magnetic gap, slots in the, rim of said E-shaped magnet, said slotscommunicating. with said groove in said inner pole piece, means fixing, said magnet and sound head in position relative to saiduppenhousing, and alowerhousing, of predetermined volume afiixed to .said upper'housing at the peripheries thereof, saidvolume of said lower housing serving to improve the, response of the transducer.

6.. In a driver, unit for an, electrical transducer, in combination, a sound head comprising a diaphragmcarryinga voice coil, anupper housing member, means for fixingthe relative position oi? said upper housing member and said sound head, a generally cylindrical, permanent magnet of an E-shaped cross-section, an inner circular pole, piece, a concentric outer annular pole piece, anon-magnetic washerfixed to said inner and outer pole pieces and spacing said pole pieces to forman annular magnetic gap therebetween, holes in said Washer to form, an acoustic resistance, a. central hole insaid inner keeper, a groove across the inner circular pole of said magnet communicatingwith said hole and communicating also with .the annular groove in said magnet, said-first groove beingofa size to form an acoustic resistanca'an annulargroove in said outer keeper, and an annular flange on said sound head engaging said,,annular groove and positioning the keepers with respect to said sound head,'with the voice coil in the annular magnetic gap.

7. In a driver unit for an electrical transducer, in; combination; asoundhead comprising a diaphragm carrying a voice coil, an upperhousing member, means for fixing the relative position of saidupper housing member and said sound head, a generally cylindrical permanent magnet ofan E-shaped cross-section having an inner circular pole-andan outerconcentric annular pole, an innercircular pole piece, a concentric outer annular pole piece, a non-magnetic washer fixed to, said inner and outer pole pieces said keepers to form a said magnetic gap therebetweenholes-insaid washer'to'fo-rm an acoustic resistance,; a,central hole in said inner pole piece, agrooveracross saidinner circular pole of said magnet communicating with saidhole and communicatingalso withtheannular groove in said magnet, said first; groove being of asize to form an acoustic; resistance, an annular grooveiin said outer keeper, an annular fiange,yon,said sound head engaging said annular groove and position ing the keepers with respect to said sound head,

with the voice coil in the annular magnetic gap, slots in the rim of said E-shaped magnet, said slots communicating with said groove in 'sai inner pole, means fixing said magnet and sound head in position relative to said upper housing,

and a lower housing of predetermined volume affixed to said upper housing at the peripheries thereof, said volume of said lower housing serving to improve the response of the transducer.

8. In a driver unit for an electrical transducer, in combination, a sound head comprising a diaphragm carrying a voice coil, an upper housing member, means for fixing the relative position of said upper housing member and said sound head, a generally cylindrical permanent magnet of an E-shaped cross-section having an inner circular pole and an outer concentric annular pole, an inner circular pole piece, a concentric outer annular pole piece, a non-magnetic washer fixed to said inner and outer pole pieces and spacing said pole pieces to form a magnetic gap therebetween, holes in said washer to form an acoustic resistance, a central hole in said inner pole piece, a groove across the face of said inner pole piece adjacent the inner circular magnet pole and communicating with said hole and communicating also with the annular groove of said E-shaped magnet, said first groove being of a size to form an acoustic resistance, an annular groove in said outer keeper, and an annular flange on said sound head engaging said annular groove .and positioning the keepers with respect to said sound head, with the voice coil in the annular magnetic gap.

9. In a driver unit for an electrical transducer,

in combination, a sound head comprising a diaphragm carrying a voice coil, an upper housing member, means for fixing the relative position of said upper housing member and said sound head, a permanent magnet of an E-shaped cross-section having an inner circular pole and an outer concentric annular pole, an inner circular pole piece, a concentric outer annular pole piece, a non-magnetic washer fixed to said inner and outer pole pieces and spacing said pole pieces to form a magnetic gap therebetween, holes in said washer to form an acoustic resistance, a central hole in said inner pole piece, a groove across the face of said inner pole piece adjacent the inner circular magnet pole and communicating with said hole and communicating also with the annular groove of said E-shaped magnet, said first groove being of a size to form an acoustic resistance, an annular groove in said outer pole piece, an annular flange on said sound head engaging said annular groove and positioning the pole piece with respect to said sound head, with the voice coil in the annular magnetic gap, slots in the rim of said E-shaped magnet, said slots communicating with said groove in said inner pole piece, means fixing said magnet and sound head in position relative to said upper housing, and. a lower housing of predetermined volume affixed to said upper housing at the peripheries thereof, said volume of said lower housing serving to improve the response of the transducer.

10. In a driver unit for an electrical transducer, in combination, a sound head comprising a diaphragm carrying a voice coil, an upper housing member, means for fixing the relative position of said upper housing member and said sound head, a permanent magnet of an E-shaped crosssection having an inner circular pole and an outer concentric annular pole, an inner circular pole piece, a concentric outer annular pole piece, a non-magnetic washer fixed to said inner and.

outer pole pieces and spacing said pole pieces to form a magnetic gap therebetween, holes in said washer to form an acoustic resistance, a, central hole in said inner pole piece, a groove across the face of said inner pole piece adjacent the inner circular magnet pole and communicating with said hole and communicating also with the annular groove of said E-shaped magnet, said first groove being of a size to form an acoustic resistance, an annular groove in said outer keeper, an annular flange on said sound head engaging said annular groove and positioning the pole pieces with respect to said sound head, with the voice coil in the annular magnetic gap, slots in the rim of said E-shaped magnet, said slots communicating with said groove in said inner pole piece, means fixing said magnet and sound head in position relative to said upper housing, a cupshaped lower housing of predetermined internal volume, the rim of said housing being adapted to fit against the rim of said upper housing, bosses on said interior surface of said lower housing, grooves in said bosses, a resilient gasket extending around the interior surface of said lower housing and held in position by being inserted in said grooves, and means for holding said lower housing in position against said upper housing with the rim of said housing in contact with both the annular resilient gasket and the rim of said lower housing.

11. A driver unit for an electrical transducer of the type comprising a diaphragm, one surface of which is exposed directly to the atmosphere, and having a voice coil operating in a magnetic gap between an inner circular pole piece and a concentric annular outer pole piece, means securing said pole pieces in fixed relation one with the other, and means forming an acoustic resistance comprising, in combination, a central hole in said inner pole piece and a diametrically extending groove across the adjacent face of the inner magnetic pole, said hole and groove forming a passage permitting controlled egress of air from the opposite side of the diaphragm.

12. A driver unit for an electrical transducer of the type comprising a diaphragm, one surface of which is exposed directly to the atmosphere, and having a voice coil operating in a magnetic gap between an inner circular pole piece and a concentric annular outer pole piece, means securing said pole pieces in fixed relation one with the other, and means forming an acoustic resistance comprising, in combination, a central hole in said inner pole piece and a diametrically extending groove in the surface of the inner pole piece adjacent the inner circular magnetic pole piece, said hole and groove forming a passage permitting controlled egress of air from the opposite side of the diaphragm.

13. A driver unit for an electrical transducer of the type comprising a diaphragm, one surface of which is exposed directly to the atmosphere, and having a voice coil operating in a magnetic gap between an inner circular pole piece and a concentric annular outer pole piece, means securing said pole pieces in fixed relation one with the other, and means forming an acoustic resist ance comprising, in combination, a central hole in said inner pole piece, a diametrically extending groove across the adjacent face of the inner magnetic pole, and a diametrically extending groove in the surface of the inner pole piece adjacent the inner circular magnetic pole piece, said hole and grooves forming a passage permitting The following references are of record in the file of this patent:

10 UNITED STATES PATENTS controlled egress of air from the opposite side Number Name Date of the diaphragm 1 766 473 Wente June 24 1930 SIDNEY LEVY- 1,838,027 Clarke Dec. 22, 1931 5 1,954,966 Thuras Apr. 17, 1934 REFERENCES CITED 2,401,328 Black June 4, 1946 

